Vehicle Comprising a Track Device

ABSTRACT

A vehicle comprising at least a first wheel ( 6 ) mounted in a first side area of the vehicle and a second wheel ( 6 ′) mounted in a second side area of the vehicle is disclosed. The vehicle comprises a track device ( 8 ) configured to be brought into engagement with the ground ( 10 ). The vehicle comprises a control member ( 32 ) configured to adjust the pressure with which the track device engages the ground, wherein the pressure is determined on the basis of measurements performed by one or more detection members configured to detect one or more variable parameters of the vehicle or external information received by the vehicle.

FIELD OF INVENTION

The present invention generally relates to a vehicle comprising a trackdevice. The invention more particularly relates to a vehicle configuredto control the pressure with which the track device engages the ground.

PRIOR ART

When driving a vehicle on stable ground (e.g. a road), it is optimum toreduce the vehicle-ground contact area in order to minimise the frictionand wear on the wheels. This is typically achieved by applying a largetyre pressure and/or by reducing the number of wheels in order to reducethe vehicle-ground contact area.

However, when driving a vehicle in a field, it is beneficial to have alarge vehicle-ground contact area in order to reduce the pressureexerted against the ground (e.g. to reduce damage caused by the drivingoperation). This may be done by mounting additional wheels on thevehicle or by decreasing the tyre pressure in order to achieve more“flat” tyres. An alternative is to apply a tracked vehicle equipped withtracks. Hereby, the vehicle is able to reach all destinations withoutdamaging the ground even if the ground is soft. Further, the vehicle canbe loaded to a greater extent.

In several countries, farmers aim for driving into the fields as earlyas possibly in the spring time. However, mud in the fields makes itimpossible to drive in the fields with heavy agricultural machinerywithout damaging the fields. Both with the purpose of protecting a fieldfrom damage caused by high pressure exerted against the ground by theagricultural machinery, and with the purpose of getting driving accessto a field in the spring time, and with the purpose of increasing thetotal load of the agricultural machinery without damaging the ground, itis necessary to be able to lower the pressure exerted against the groundby the agricultural machinery. It is well known that soil compaction—which is the process in which a stress applied to a soil causesdensification as air is displaced from the pores between the soilgrains—is a serious problem for farmers. Soil compaction is often theresult of heavy machinery, such as agricultural machinery compressingthe soil.

Therefore, it is an object of the invention to provide a vehicle bymeans of which it is possible to control (and e.g. lower) the pressureexerted by the wheels and track device of the vehicle against the groundin order to prevent soil compaction.

Due to the fact that agricultural machinery has to drive both on stableground and in a field, one has to make a compromise in order to providea solution that satisfies both ground conditions (stable ground drivingand field driving). Therefore, the prior art vehicles are notwell-suited for both driving on solid ground and in fields. Furthermore,when using prior art tracked and wheeled vehicles, there is risk forexperiencing a situation in which the pressure exerted against theground by the tracks exceeds the required pressure exerted by the wheelsagainst the ground for providing a sufficiently large normal force formaintaining a sufficiently large road grip. Furthermore, it is desirableto be able to control the pressure which the tracks and wheels exert onthe ground e.g. during varying driving conditions (varying groundcharacteristics or load conditions). Accordingly, there is need for animproved vehicle and a method to control the pressure which the tracksand wheels exert on the ground.

Therefore, it is an object of the present invention to provide a vehiclewhere the pressure with which the track device engages the ground can becontrolled. It is moreover an object of the present invention to providea vehicle where the pressure with which the track device engages theground can be controlled in a manner that secures that the vehicle isalways capable of driving when the tracks exert a pressure on the grounde.g. in order to prevent soil compaction.

It is a further object of the present invention to provide a method tocontrol a tracked vehicle in order to control the pressure which thetracks and wheels exert on the ground and to allow driving when thetracks are activated.

Moreover, the prior art tracked vehicles are provided with track devicesarranged in areas of the vehicle that makes it difficult to turn thevehicle. Accordingly, it is an object of the present invention toprovide an easy turnable vehicle. Thus, there is a need for a vehiclewhich reduces or even eliminates the above-mentioned disadvantages ofthe prior art.

SUMMARY OF THE INVENTION

The object of the present invention can be achieved by a vehicle asdefined in claim 1. Preferred embodiments are defined in the dependentsub claims, explained in the following description and illustrated inthe accompanying drawings.

The vehicle according to the invention is a vehicle comprising at leasta first wheel mounted in a first side area of the vehicle and a secondwheel mounted in a second side area of the vehicle, which vehiclecomprises a track device configured to be brought into engagement withthe ground, wherein the vehicle comprises a control member configured toadjust the pressure with which the track device engages the ground,wherein the pressure is determined on the basis of measurementsperformed by one or more detection members configured to detect one ormore variable parameters of the vehicle or external information receivedby the vehicle.

Hereby, it is possible to provide a vehicle in which the pressure withwhich the track device and the wheels engage the ground can becontrolled and wherein driving is possible when the tracks areactivated. The pressure with which the track device and the wheelsengage the ground can be controlled on the basis of measurementsperformed by one or more detection members or external informationreceived by the vehicle. The vehicle hereby makes it possible to avoidsoil compaction.

The vehicle according to the invention is a vehicle comprising at leasta first wheel mounted in a first side area of the vehicle and a secondwheel mounted in a second side area of the vehicle. The first side areamay be the left side of the vehicle, whereas the second side area may bethe right side of the vehicle or vice versa.

The vehicle may comprise one or more wheels in the first side area andmay comprise one or more wheels in the second side area.

The vehicle may be agricultural machinery such as a tractor, a slurrytanker) a manure spreader, a cutter wagon, a combine harvester, a foragewagon, a bead harvester, a potato harvester, a sprayer, a tractortrailer, a crop sprayer or a forester vehicle by way of example.

The vehicle comprises a track device configured to be brought intoengagement with the ground. The track device may be any suitable type oftrack device or belt (also known as continuous track or caterpillartrack). The track device may also be a unit comprising a plurality ofrotatably mounted wheels or idlers configured to be brought intoengagement with the ground.

It may be an advantage that the one or more variable parameters of thevehicle are one or more of the following:

-   a) the slippage and/or road grip of one or more of the wheels;-   b) the axle load and/or the load of the vehicle or of a container of    the vehicle;-   c) the tyre pressure of one or more of the wheels;-   d) the measured motor power and/or the velocity of the vehicle.-   e) the visual detection of the content in a container;-   f) the pressure in a structure;-   g) the distance from a predefined position to an object (e.g. a    fluid or the content of a container).

By detecting the slippage and/or road grip of one or more of the wheels,it is possible to adjust the pressure with which the track deviceengages the ground in order to secure that the normal force acting onthe wheels is sufficiently large. It may be an advantage that theslippage and/or road grip of one or more of the wheels is measured on acontinuous basis. Furthermore, it may be beneficial that slippage and/orroad grip is detected for several wheels. In one embodiment according tothe invention, the slippage and/or road grip is detected for all wheels.

The slippage and/or road grip may be detected by measuring the speed ofthe vehicle and the ground engaging portion of the wheel. The speed ofthe ground engaging portion of the wheel may be determined by measuringthe rotational speed of the wheel or by means of a velocity sensor.

In one embodiment according to the invention, the vehicle is capable ofminimising the pressure which any of the wheels or the track deviceexerts on the ground, and at the same time, securing a sufficient gripto drive the vehicle by means of the wheels. Hereby, the track devicedoes not need to be provided with a drive unit for driving the trackdevice. Moreover, a high tyre pressure may be used.

By detecting the axle load and/or the load of the vehicle or of acontainer of the vehicle, it is possible to account for soilcharacteristics (e.g. a dry field or a sludge field). The axle load maybe detected by means of load sensors such as strain gauges.Alternatively, the axial load may be detected by means of one or morepressure sensors or weighing sensors.

The load of the vehicle or of a container of the vehicle may be measuredby one or more weighing sensors. By way of example, the weight of atractor trailer or a flatbed may be detected by means of one or morestrain gauges, pressure sensors or weighing sensors.

In one embodiment of a vehicle according to the invention, the controlmember is configured to (preferably on a continuous basis) provide aconstant pressure exerted by the wheels on the ground by regulating thepressure exerted by the track device on the ground, when the load of avehicle varies. This may be achieved by measuring the load (e.g. theload of a trailer, tank or another container of a vehicle) and adjustingthe pressure with which the track device engages the ground. If load isadded to the vehicle (e.g. a slurry spreader, a cutter wagon or acombine harvester), the track device will automatically be regulated toprovide a larger pressure towards the ground in order to reduce thepressure exerted by the wheels on the ground. The constant pressureexerted by the wheels on the ground may be defined to maximum 0.5 kg/cm²or 1.0 kg/cm².

For safety reasons, it may be beneficial to detect the tyre pressure ofone or more of the wheels. This may be done by means of tyre pressuresensors that may be configured to communicate wirelessly with a centralcontrol unit of the vehicle. It may be an advantage that the trackdevice is configured to be automatically brought into engagement withthe ground and support the vehicle in case that a tyre pressure drop isdetected.

By measuring the motor power and/or the velocity of the vehicle, it ispossible to detect the external “resistance” e.g. when a farmer isharrowing a field. If the harrow pulls the vehicle into the ground, theresistance will increase, and thus it may be an advantage to bring thetrack device into engagement with the ground and use the control memberto increase the pressure with which the track device engages the ground.Hereby, the harrow may be moved upwards in order to reduce theresistance and hereby reduce the energy consumption by increasing thefuel economy.

Visual detection of the content in a container may be carried out bymeans of any suitable visual detection means including cameras. Hereby,it is possible to detect the content of a trailer, wagon or tank for thepurpose of regulating the pressure with which the track device engagesthe ground.

It is possible to detect the pressure in a structure in order toregulate the pressure with which the track device engages the ground onthe basis of this pressure. The pressure may be measure in any suitablestructure of the vehicle e.g. in a hydraulic system of the vehicle.

It is possible to measure the distance from a predefined position to anobject in order to determine the load of a trailer, wagon or tank loadedwith e.g. wheat, sand of a fluid. It is possible to carry out distancemeasurements of the level in a trailer, wagon, manure spreader tank og agrain tank of a combine harvester by way of example. By detecting thelevel, the load and thus the pressure with which the wheels engage theground can be estimated. Accordingly, the pressure with which the trackdevice shall engage the ground (e.g. for reducing the the pressure withwhich the wheels engage the ground) can be determined.

It may be advantageous that the vehicle comprises a control memberconfigured to adjust the pressure with which the track device engagesthe ground on the basis of geographical data measured by a sensor memberof the vehicle or received by the vehicle. Hereby, the track device maybe used in dependency of geographical data allowing the track device ofthe vehicle to be controlled in a manner in which soil characteristics(e.g. a dry field or a sludge field) can be taken into account.

The sensors and/or detection members may be configured to communicatewirelessly with a central control unit being part of the control memberof the vehicle. Furthermore, it may be an advantage that the centralcontrol unit is directly or indirectly connected to and adapted tocontrol one or more activation devices.

It may be advantageous that the vehicle comprises means for bringing thetrack device into a configuration in which the track device is not inengagement with the ground. Hereby, the vehicle is configured to bedriven on solid ground such as asphalt only by means of the wheels.

It may be advantageous that the track device comprises drive means fordriving the track device. Hereby, it is possible to increase themobility of the vehicle. In case the vehicle is a non-motorised vehicle,the vehicle may be provided with drive means enabling the vehicle to beused in more demanding applications.

The drive means may be a hydraulic motor or actuator configured to beconnected to the hydraulic system of the vehicle or to the hydraulicsystem of a motorised vehicle pulling the non-motorised vehicle.

The drive means may be an electric motor or actuator configured to beconnected to the electric system of the vehicle or to the electricsystem of a motorised vehicle pulling the non-motorised vehicle.

It may be an advantage that the track device is detachably mounted tothe vehicle. Hereby, it is possible to apply the same track device onseveral different vehicles by turns. It may be an advantage that thetrack device is configured to be hydraulically and/or electricallyconnected to different vehicles.

By using a detachably mounted track device, the track device may beinstalled subsequently.

It may be an advantage that the vehicle comprises control meansconfigured to adjust and/or control the pressure with which the trackdevice engages the ground. Hereby, it is possible to adjust and/orcontrol the pressure of the vehicle towards the ground and meetrequirements e.g. made by authorities or to avoid damage to crops.

It may be an advantage that the track device comprises a hydraulicand/or electrical actuator configured to be connected to the hydraulicsystem of the vehicle and/or to the electric system of the vehicle.Hereby, it is possible to apply the existing system of the vehicle todrive the actuator(s) of the track device of the vehicle.

It may be beneficial that the vehicle comprises means for displacing thetrack device along an axis extending perpendicular to the direction oftravel.

It may be beneficial that the vehicle comprises means for displacing thetrack device along a horizontal axis extending perpendicular to thedirection of travel.

Hereby, the track device can be displaced in order to fit the specificdistances between rows of cultivated plant (e.g. berry trees, beets,potatoes, wheat, oats, or corn and other grain crops).

It may be beneficial that the track device is movably, e.g. slidablyarranged at the vehicle in such a manner that the track device may berearranged. Hereby, it is possible to change the configuration of thetrack device relative to the vehicle if desired in that way allowing forincreasing the stability of the vehicle.

It may be beneficial that the vehicle comprises means for ensuring thatthe track device engages the ground with a predefined pressure definedon the basis of measurements made by the vehicle, preferably a constantpressure. Hereby, it is possible to control the pressure with which thetrack device engages the ground.

It may be an advantage that the vehicle comprises means for ensuringthat the track device engages the ground with a predefined constantpressure.

It may be beneficial that the track device is arranged below a shaftconnecting the first wheel and the second wheel of the vehicle.

Hereby, it is possible to apply the track device to reduce the pressurewith which the wheels engage the ground. The shaft does no need to be arotating shaft. The shaft may be a rod member, to which the first andsecond wheels are rotatably mounted. Accordingly, each wheel may bedriven by a separate motor. The shaft may have a rectangular (e.g.square) cross-section.

It may be advantageous that the track device is arranged to support aportion of the shaft that extends between the first wheel and the secondwheel of the vehicle.

Accordingly, the track device can relieve the pressure with which thewheels engage the ground.

The method according to the invention is a method for controlling atracked and wheeled vehicle comprising a track device configured to bebrought into engagement with the ground, which vehicle comprises acontrol member configured to adjust the pressure with which the trackdevice engages the ground, wherein the method comprises the steps of:

-   -   detecting one or more variable parameters measured by one or        more detection members or receiving external information;    -   adjusting the pressure with which the track device engages the        ground on the basis of the detected parameter(s) or external        information received by the vehicle.

Hereby, it is possible to control the pressure with which the trackdevice engages the ground in such a manner that the vehicle is alwayscapable of driving when the tracks exert a pressure against the ground.

It may be advantageous that the one or more variable parameters measuredby one or more detection members are one or more of the following:

-   a) the slippage and/or road grip of one or more of the wheels;-   b) the axle load and/or the load of the vehicle or of a container of    the vehicle;-   c) the tyre pressure of one or more of the wheels;-   d) the measured motor power and/or the velocity of the vehicle.-   e) the visual detection of the content in a container;-   f) the pressure in a structure;-   g) the distance from a predefined position to an object (e.g. a    fluid or the content of a container).

By applying the detected slippage and/or road grip of one or more of thewheels, it is possible to adjust the pressure with which the trackdevice engages the ground in order to secure that the normal forceacting on the wheels is sufficiently large. It may be an advantage thatthe slippage and/or road grip of one or more of the wheels is measuredon a continuous basis. Furthermore, it may be beneficial that slippageand/or road grip is detected for several wheels. In one embodimentaccording to the invention, the slippage and/or road grip is detectedfor all wheels.

In one embodiment according to the invention, the one or more variableparameters measured is the pressure with which the track device and/orthe wheels engage the ground. In one preferred embodiment according tothe invention, the pressure is kept below a predefined maximum pressurelimit of e.g. 1 kg/cm³.

By applying the detected axle load and/or the load of the vehicle or ofa container of the vehicle, it is possible to account for soilcharacteristics (e.g. a dry field or a sludge field). The axle load maybe detected by means of load sensors such as strain gauges.Alternatively, the axial load may be detected by means of one or morepressure sensors or weighing sensors.

By applying the detected tyre pressure of one or more of the wheels, thepressure exerted on the ground by the track device may be increased if atyre pressure drop is detected.

By applying the detected motor power and/or the velocity of the vehicle,it is possible to determine the external “resistance” e.g. when a farmeris harrowing a field. The pressure exerted on the ground by the trackdevice may be increased in order to lower the resistance caused by aharrow.

Visual detection of the content in a container may be carried out bymeans of any suitable visual detection means including cameras. Hereby,it is possible to detect the content of a trailer, wagon or tank for thepurpose of regulating the pressure with which the track device engagesthe ground.

It is possible to detect the pressure in a structure in order toregulate the pressure with which the track device engages the ground onthe basis of this pressure. The pressure may be measure in any suitablestructure of the vehicle e.g. in a hydraulic system of the vehicle.

It is possible to measure the distance from a predefined position to anobject in order to determine the load of a trailer, wagon or tank loadedwith e.g. wheat, sand of a fluid. It is possible to carry out distancemeasurements of the level in a trailer, wagon, manure spreader tank og agrain tank of a combine harvester by way of example. By detecting thelevel, the load and thus the pressure with which the wheels engage theground can be estimated. Accordingly, the pressure with which the trackdevice shall engage the ground (e.g. for reducing the the pressure withwhich the wheels engage the ground) can be determined.

It may be an advantage that the method comprises the step of adjustingthe pressure with which the track device engages the ground on the basisof geographical data measured by a sensor member of the vehicle orreceived by the vehicle. Hereby, it is possible to account forgeographical data (e.g. country or region specific variations) whencontrolling the track device.

It may be beneficial that the geographical data comprises informationabout the soil type of the ground in the area below and/or around thevehicle. Hereby, it is possible to account for soil characteristics(e.g. a dry field or a sludge field) when controlling the track device.The geographical data may include stored data (e.g. saved from last yearby the driver of the vehicle). The stored data may include driveradjustment made base on the driver.

It may be an advantage that the track device is mounted in the centrearea between the first side area and the second side area in closerdistance to the central portion of the vehicle than the first side areaand the second side area. Hereby, it is possible to provide a vehiclethat is easy to turn and navigate. The vehicle is easy to turn, and theweight of the vehicle can be distributed onto regions in a distance fromthe first side area and the second side area.

The central portion of the vehicle may be the longitudinal axis of thevehicle.

It may be beneficial that the vehicle is a non-motorised vehicle. Anon-motorised vehicle may be a trailer or a sprayer by ways of example.

It may be advantageous that the track device comprises two paralleltrack device members. Hereby, it is possible to increase the total areaeven more.

The vehicle according to the invention may comprise one track devicemember and thus one belt or a number of wheels.

The vehicle according to the invention may comprise two track devicemembers and thus two belts or two sets of wheels.

The vehicle according to the invention may comprise three track devicemembers and thus three belts or three sets of wheels.

The vehicle according to the invention may comprise four or more trackdevice members and four or more sets of wheels.

It may be an advantage that the track device comprises means forhorizontally displacing the track device from a first position into oneor more further horizontal positions within the vehicle (e.g. from thecentral portion of the vehicle to the lateral portion(s) of thevehicle).

It may be beneficial that the track device comprises a suspension memberhaving an attachment member provided at the distal end, where thesuspension member is attached to a connection member at the proximalend, which connection member comprises a first connection element and asecond connection element.

It may be an advantage that the track device comprises at least onehydraulic actuator rotatably attached to the first connection element bymeans of a joint. The second connection element may be rotatablyattached to the base member by means of one or more additional joints.

It may be an advantage that the track device is mounted in such a mannerthat the pressure from the vehicle towards the track device is providedin the medial region of the track device when the track device isbrought into engagement with the ground.

It may be an advantage that the track device is mounted in such a mannerthat the pressure from the vehicle towards the track device is providedat the centre line within the medial region of the track device when thetrack device is brought into engagement with the ground.

It may be beneficial that the vehicle comprises means for ensuring thatthe track device engages the ground with a predefined pressure,preferably a constant pressure.

Hereby, it is possible to control the pressure by which the track deviceengages the ground.

It may be advantageous that the vehicle comprises one or more pressurecompensators being in fluid communication with the track device.

Hereby, the pressure compensators can absorb shocks caused by the trackdevice when being in contact with bumps and holes. The pressurecompensators can absorb shocks by receiving or releasing hydraulic oil.

The compensators may be integrated in the track device.

One method according to the invention is a method for producing a trackdevice, wherein the method comprises the step of applying a used tyre,preferably a tyre from a tractor, to produce the track device member ofthe track device.

It may be an advantage that the method comprises the step of cutting aused tyre, preferably a used tyre of a tractor, and applying it as thetrack device member in a track device of a vehicle according to theinvention.

It may be beneficial that the method comprises the step of arranging theused tyre in a non-circular configuration, preferably a configuration inwhich the tyre is formed as a flat belt or a V-belt.

In one embodiment, the method according to the invention is a method forproducing a track device of a vehicle according to the invention,wherein the method comprises the step of applying a used tyre,preferably a tyre from a tractor, to produce the track device member ofthe track device.

DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detaileddescription given herein below. The accompanying drawings are given byway of illustration only, and thus, they are not limitative of thepresent invention. In the accompanying drawings:

FIG. 1 a) shows a schematic side view of a vehicle according to theinvention;

FIG. 1 b) shows a schematic back view of the vehicle shown in FIG. 1 a);

FIG. 2 a) schematically shows a perspective view of a track device of avehicle according to the invention;

FIG. 2 b) shows a schematic side view of another track device accordingto the invention;

FIG. 2 c) shows a perspective view of a track device of a vehicleaccording to the invention mounted on a tractor trailer;

FIG. 3 a) shows a perspective top view of a vehicle according to theinvention;

FIG. 3 b) shows a schematic side view of a vehicle according to theinvention in which the track device is in a raised position;

FIG. 3 c) shows a schematic side view of a vehicle according to theinvention in which the track device is in a lowered position and thussupports the vehicle;

FIG. 4 a) shows a schematic bottom view of a track device of a vehicleaccording to the invention;

FIG. 4 b) shows a schematic top view of a track device of a vehicleaccording to the invention;

FIG. 4 c) shows a schematic view of a track device according to theinvention seen from a second end;

FIG. 4 d) shows a schematic view of a track device according to theinvention seen from a first end;

FIG. 5 a) shows a schematic view of a loaded prior art tractor trailerand the pressure exerted against the ground;

FIG. 5 b) shows a schematic view of a loaded tractor trailer accordingto the invention and the pressure exerted against the ground;

FIG. 5 c) shows a schematic view of an unloaded tractor traileraccording to the invention and the pressure exerted against the ground;

FIG. 6 a) shows a schematic view of a motorised vehicle according to theinvention;

FIG. 6 b) shows a schematic back view of a tractor trailer according tothe invention;

FIG. 7 shows schematic views of how the configuration of a track deviceof a vehicle according to the invention can be changed;

FIG. 8 shows a diagram of a proportional, integral and derivative (PID)control system according to the invention;

FIG. 9 shows different views of a tractor trailer according to theinvention;

FIG. 10 a) shows a first rotation device according to the invention

FIG. 10 b) shows a second rotation device according to the invention;

FIG. 10 c) shows a back view of a tractor trailer according to theinvention;

FIG. 11 A) shows a schematic side view of a vehicle according to anembodiment of the invention in which the track device engages the ground

FIG. 11 b) shows a schematic side view of the vehicle shown in FIG. 11b) in a configuration in which the track device does not engages theground and

FIG. 11 c) shows a schematic view of a track device attached to a shaftextending between a first wheel and a second wheel.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the drawings for the purpose of illustratingpreferred embodiments of the present invention, a vehicle 2 of thepresent invention is illustrated in FIG. 1 a).

FIG. 1 a) illustrates a schematic side view of a vehicle 2 according tothe invention. The vehicle 2 is a tractor trailer comprising a boxmember rotatably mounted to a frame member 12. A tipping member 16extends between the frame member 12 and the back of the box member 18.The tipping member 16 is slidably arranged and configured to be extendedhereby causing a tipping action needed to empty the box member 18. Thetipping member 16 may be hydraulic powered; however, an electricactuator may be used as an alternative.

The vehicle 2 comprises a support member 14 resting on the ground 10 andbeing arranged at the front end of the vehicle 2. The vehicle 2comprises two sets of wheels 6′ rotatably attached to the frame member12. The vehicle 2 moreover comprises a track device 8 attached to theframe member 12. The track device 8 comprises a suspension member 20extending between the frame member 12 and the lower portion of the trackdevice 8.

The vehicle 2 comprises a control box 106 configured to activateactivation means (e.g. a hydraulic cylinder or an electric actuator) inorder to change the vertical position of the track device 8 and thepressure with which the track device 8 engages the ground 10. Thevehicle 2 comprises a tyre pressure sensor 110 arranged at the wheel 6′and a velocity sensor 108 also attached to the wheel 6′. The tyrepressure sensor 110 and the velocity sensor 108 are configured towirelessly communicate with the control box 106. It is indicated thatthe tyre pressure sensor 110 and the velocity sensor 108 send wirelesssignals 112 to the control box 106.

Hereby, the tyre pressure sensor 110 and the velocity sensor 108 candetect pressure and velocity data and send the data to the control box106. The control box 106 can determine if the pressure with which thetrack device 8 engages the ground 10 should be unchanged, be increasedor be decreased.

The track device 8 may be lowered in order to bring it in contact withthe ground 10 in order to reduce the peak pressure exerted against theground 10 by the wheels 6′. The vehicle 2 is capable of preventing soilcompaction.

The track device 8 may be equipped with drive means in order to motorisethe vehicle 2. The drive means may be hydraulic or electric.

FIG. 1 b) illustrates a schematic back view of the vehicle 2 accordingto the invention shown in FIG. 1 a). The vehicle 2 comprises a first setof wheels 6 arranged in the left side area 58 of the vehicle 2 and asecond set of wheels 6′ arranged in the right side area 58′ of thevehicle 2.

A track device 8 is arranged in the central area 60 between the leftside area 58 of the vehicle 2 and the right side area 58′ of the vehicle2. The track device 8 comprises a first track device member 46 and asecond track device member 48. The first track device member 46 and thesecond track device member 48 extend parallel to each other.

The vehicle 2 comprises a box member 18 configured to receive items suchas grain, waste or straw.

FIG. 2 a) illustrates a schematic perspective view of a track device 8of a vehicle (not shown) according to the invention. The track device 8comprises a base member 36 formed as an elongated rod member having abasically rectangular cross-section. A plurality of bottom supportwheels 30 are rotatably attached to the base member 36.

The base member 36 comprises a first end portion 40 and a second endportion 38. A front wheel 26 is rotatably mounted to the second endportion 40, while a rear wheel 24 is rotatably mounted to the second endportion 38.

A top support wheel 28 is rotatably mounted to the base member 36.

The track device 8 comprises a track member 22 extending at the outsideperiphery of the bottom support wheels 30, the front wheel 26, the rearwheel 24 and the top support wheel 28. The track member 22 may be aterrain track. The track member 22 may be a portion (e.g. the midportion) of a used tractor tyre.

Tensioning of the track device member 22 may be carried out bydisplacing the end portions 38, 40 axially relative to the base member36 e.g. my beans of a mechanical screw member.

The track device 8 comprises a suspension member 20 having an attachmentmember provided at the distal end. At the proximal end, the suspensionmember 20, and??? a connection member 34 comprising a first connectionelement 34′ and a second connection element 34″ is attached.

The track device 8 comprises a hydraulic actuator 32 rotatably attachedto the first connection element 34′ by means of a joint 44. The secondconnection element 34″ is rotatably attached to the base member 36 bymeans of joints 42 (only one is visible in FIG. 2 a).

The attachment member 50 is configured to be rotatably attached to theframe member of a vehicle (see FIG. 2 c). Similarly, the actuator 32 isconfigured to be rotatably attached to the frame member of a vehicle inits distal end.

When the track device 8 is attached to a vehicle (e.g. like illustratedin FIG. 2 c), the track device 8 may be activated by means of anelectrical control box that may be electrically connected to e.g. one ormore electrically controllable valves.

Accordingly, the vertical position of the base member 36 and thus thetrack device member 22 may be changed by means of the actuator 32.

FIG. 2 b) illustrates a side view of another track device 8 according tothe invention. The track device 8 comprises some of the same element asthe track device 8 shown in FIG. 2 a). The base member 36, the first endportion 40 and a second end portion 38 correspond to the ones shown inFIG. 2 a). Likewise, the track member 22, the front wheel 26, the rearwheel 24, the top support wheel 28 and the bottom support wheels 30correspond to the ones used in the track device 8 shown in FIG. 2 a).

The track device 8 in FIG. 2 b), however, comprises two parallelextending hydraulic actuators 32 and two parallel extending suspensionmembers 20. The hydraulic actuators 32 are rotatably attached to theconnection members 34.

FIG. 2 c) shows a perspective view of a vehicle 2 according to theinvention. The vehicle 2 is a tractor trailer comprising a track device8 mounted on a basically V-shaped frame member 12 of the tractor trailer2.

A first set of wheels 6 and a second set of wheels 6′ are rotatablymounted to the frame member 12. A support member 14 is provided near thefront end of the frame member 12. A box member 18 is rotatably attachedto the frame member 12, and an extendable tipping member 16 extendsbetween the frame member 12 and the back of the box member 18.

The track device 8 comprises a first track device member 46 and a secondtrack device member 48 corresponding to the ones shown in FIG. 2 b). Itcan be seen that the track device 8 comprises a suspension member 20formed as an elongated rod with a rectangular cross-section. Thesuspension member 20 is mechanically attached to an attachment member 50rotatably attached to the frame member 12.

FIG. 3 a) illustrates a perspective top view of a vehicle 2 according tothe invention. The vehicle 2 corresponds to the one shown in FIG. 2 c).The vehicle 2 is a tractor trailer comprising a first set of wheels 6and a second set of wheels 6′ rotatably attached to the frame member 12of the vehicle 2 by means of a shaft member 52 extending between the twoset of wheels 6, 6′.

The vehicle 2 comprises a box member 18 that is brought into a tippingconfiguration by means of a tipping member 16 extending between theframe member 12 and the back of the box member 18.

The vehicle 2 rests on the two sets of wheels 6, 6′ and on the supportmember 14 slidably arranged within a corresponding channel provided inthe front portion of the frame member 12.

The track device 8 is mounted in the same way as illustrated in FIG. 2c).

FIG. 3 b) illustrates a side view of the vehicle 2 shown in FIG. 3 a).The vehicle 2 is seen from the right side. The vehicle 2 comprises twosets of wheels of which only one set 6′ is visible. A track device 8 ismounted at the frame member 12 of the vehicle 2 by means of a suspensionmember 20. The box member 18 has been arranged in a tippingconfiguration by extending the tipping member (hydraulic telescopic arm)16 extending between the frame member 12 and the back of the box member18.

The track device 8 is arranged at a distance from the ground 10.Accordingly, the track device 8 does not engage the ground 10.Therefore, in this configuration, the track device 8 does not decreasethe peak pressure exerted against the ground 10 by the wheels 6′.However, when driving on stable ground (e.g. an asphalt road), it may bean advantage to lift up the track device 8 in order to bring the trackdevice 8 into a position in which it does not engage the ground 10 (likeillustrated in FIG. 3 b).

FIG. 3 c) illustrates a side view of the vehicle 2 shown in FIG. 3 a)and in FIG. 3 b). The only difference between FIG. 3 b) and FIG. 3 c) isthat the track device 8 has been brought into engaging contact with theground 10 in FIG. 3 c). Since the track device 8 engages the ground 10,the track device 8 reduces the peak pressure exerted against the ground10 by the wheels 6′. This is explained in further detail with referenceto FIG. 5. The vehicle 2 is capable of preventing soil compaction byreducing the pressure towards the ground.

FIG. 4 a) illustrates a schematic bottom view of a track device 8 of avehicle according to the invention. The track device 8 comprises a trackmember 22 and a connection member 34 arranged in the central portion ofthe track device 8.

A suspension member 20 mechanically attached to an attachment member 50is provided at the end portion of the track device 8.

FIG. 4 b) illustrates a schematic top view of a track device 8 shown inFIG. 4 a). It can be seen that the connection member 34 comprises afirst connection element 34′ and a second connection element 34″. Thetrack device 8 comprises a suspension member 20 extending along themiddle plane of the track device 8. The suspension member 20 ismechanically fixed to the second connection element 34″. The trackdevice 8 comprises a hydraulic actuator 32 rotatably mounted to thefirst connection element 34′.

FIG. 4 c) illustrates a schematic view of the track device 8 shown inFIG. 4 a) and in FIG. 4 b) seen from a first end. The track device 8comprises a track member 22 and a connection member 34 symmetricallyarranged at the central portion of the track device 8. The connectionmember 34 comprises a first connection element 34′ and a secondconnection element 34″ symmetrically arranged. It can be seen that theattachment member 50 is also symmetrically arranged.

FIG. 4 d) illustrates a schematic view of the track device 8 shown inFIG. 4 c) seen from a second end. It can be seen that the attachmentmember 50 comprises a central portion 56 arranged between two endportions 54. The attachment member 50 is arranged at the distal portionof the suspension member 20 mechanically attached to the secondconnection element 34″.

FIG. 5 a) illustrates a schematic view of a prior art tractor trailer 2loaded with rocks. Below the tractor trailer 2, a first and a secondgraph are shown. The first graph illustrates the force F exerted againstthe ground by the wheels 6, 6′. The first set of wheels 6 is arrangedwithin a first side area 58 of the tractor trailer 2, whereas the secondset of wheels 6′ is arranged within a second side area 58′ of thetractor trailer 2. No force is exerted against the ground within thecentre area 60 provided between the first side area 58 of the tractortrailer 2 and the second side area 58′ of the tractor trailer 2.

The force F₃ exerted by the wheels 6, 6′ against the ground within thefirst side area 58 of the tractor trailer 2 and the second side area 58′of the tractor trailer 2 is indicated in the first graph.

The pressure P₄ exerted against the ground by the first set of wheels 6corresponds to the pressure exerted against the ground by the second setof wheels 6′.

FIG. 5 b) illustrates a schematic view of the tractor trailer 2generally corresponding to the one shown in FIG. 5 a). The tractortrailer 2 shown in FIG. 5 b) is, however, equipped with a track device 8according to the invention. Below the tractor trailer 2, a first and asecond graph are shown. The first graph illustrates the force F exertedagainst the ground by the wheels 6, 6′ and the track device 8.

The first set of wheels 6 is arranged within a first side area 58 of thetractor trailer 2, and the second set of wheels 6′ is arranged within asecond side area 58′ of the tractor trailer 2. The track device 8 isarranged in the centre area 60 between the first side area 58 of thetractor trailer 2 and the second side area 58′ of the tractor trailer 2.

The force F₃ exerted against the ground by the track device 8 in thecentre area 60 is indicated. Similarly, the force F₂ exerted against theground by the wheels 6 within the first side area 58 of the tractortrailer 2 and by the wheels 6′ within the second side area 58′ of thetractor trailer 2 is indicated in the first graph.

The second graph illustrates that the pressure P₃ exerted against theground by the first set of wheels 6 corresponds to the pressure exertedagainst the ground by the second set of wheels 6′, and that thispressure P₃ is significantly lower than the pressure P₄ exerted againstthe ground by the wheels 6, 6′ in the prior art tractor trailer 2illustrated in FIG. 5 a). Moreover, the second graph illustrates thatthe pressure P₂ exerted against the ground by the track device issignificantly lower than the pressure P₃ exerted against the ground bythe wheels 6, 6′.

In FIG. 5 b), it can be seen that the track device 8 comprises a firsttrack device member 46 and a second track device member 48. The trackdevice 8 is brought into engagement with the ground, and thus thepressure P₃ exerted against the ground by the wheels 6, 6′ issignificantly reduced compared with FIG. 5 a). The pressure P₃ exertedagainst the ground by the wheels 6, 6′ of the tractor trailer shown inFIG. 5 b) is significantly decreased due to the use of the track device8.

The track device 8, however, exerts a pressure P₂ against the ground.This pressure P₂ is lower than the pressure P₃ exerted against theground by the first set of wheels 6 and by the second set of wheels 6′because the contact area of the track device is significantly largerthan the contact area of the wheels 6, 6′.

It can be seen that the vehicle 2 provided with a track device 8 iscapable of reducing the pressure exerted against the groundsignificantly even if the force F₃ exerted against the ground by thetrack device 8 in the centre area 60 is kept at a high level.

FIG. 5 c) illustrates an unloaded tractor trailer 2 according to theinvention. Below the tractor trailer 2, a first and a second graph areshown. The first graph illustrates the force F exerted against theground by the wheels 6, 6′ and the track device 8.

The first set of wheels 6 is arranged within a first side area 58 of thetractor trailer 2, whereas the second set of wheels 6′ is arrangedwithin a second side area 58′ of the tractor trailer 2. The track device8 is arranged in the centre area 60 between the first side area 58 ofthe tractor trailer 2 and the second side area 58′ of the tractortrailer 2.

The force F₃ exerted against the ground by the track device 8 in thecentre area 60 is the same as in FIG. 5 b) in which the tractor trailer2 is loaded. The force F₁ exerted against the ground by the wheels 6within the first side area 58 of the tractor trailer 2 and by the wheels6′ within the second side area 58′ of the tractor trailer 2 is indicatedin the first graph.

It can be seen that the force F₁ exerted against the ground by thewheels 6, 6′ is significantly lower than the force F₂ exerted againstthe ground by the wheels 6, 6′ in FIG. 5 b).

The second graph illustrates that the pressure P₁ exerted against theground by the first set of wheels 6 corresponds to the pressure exertedagainst the ground by the second set of wheels 6′, and that thispressure P₁ is significantly lower than the pressure P₂ exerted againstthe ground by the wheels 6, 6′ of the loaded tractor trailer 2illustrated in FIG. 5 b).

Furthermore, the second graph illustrates that the pressure P₂ exertedagainst the ground by the track device 8 corresponds to the pressureexerted against the ground by the track device 8 of the loaded tractortrailer 2 illustrated in FIG. 5 b).

When FIG. 5 c) is compared to FIG. 5 b), it can be seen that thepressure P₂ exerted against the ground by the track device 8 is the samewhen the tractor trailer 2 is loaded (FIG. 5 b) and when the tractortrailer 2 is unloaded (FIG. 5 c), respectively. This may be accomplishedby applying a control method in which the force F₃ and thus the pressureP₂ exerted against the ground by the track device 8 are kept constant.

FIG. 6 a) illustrates a schematic view of a motorised vehicle 4according to the invention. The motorised vehicle 4 is a tractorcomprising two front wheels and two rear wheels 6′. The tractor 4 isprovided with a track device 8 mounted between the two rear wheels 6′(only one of the rear wheels is visible on FIG. 6).

The track device 8 mounted on either a motorised vehicle or on anon-motorised vehicle may be controlled by several control methods. Itis possible to connect the track device 8 to the hydraulic system of thevehicle (e.g. a tractor) or to the hydraulic system of the vehicle (e.g.a tractor) pulling the vehicle. However, the track device 8 may beelectrically driven. It is possible to apply a generator that can beattached to the power take-off (PTO) shaft of a tractor or anothervehicle.

The track device 8 may be configured to be arranged in a firstconfiguration in which the track member 22 of the track device 8 ispositioned in a non-zero distance from the ground and in a secondconfiguration in which the track member 22 of the track device 8 engagesthe ground.

It is possible to apply a predefined pressure when the track member 22of the track device 8 engages the ground.

The vehicle according to the invention may comprise a control systemconfigured to vary the pressure with which the track member 22 of thetrack device 8 engages the ground. In one embodiment of a vehicleaccording to the invention, the control system may be configured toreceive information indicating the road grip of the vehicle.

Hereby, it is possible to adjust the pressure with which the trackmember 22 of the track device 8 engages the ground on the basis of theinformation indicating the road grip of the vehicle. It is possible toapply a flexible track device member (belt) or interlocking metalsegments or the threads from a used tractor tyre.

FIG. 6 b) illustrates a back view of a tractor trailer 2 according tothe invention. The tractor trailer 2 comprises two wheels 6, 6′ and atrack device 8 mounted in the centre area between the first side area(in which the left wheel 6 is mounted) and the second side area (inwhich the right wheel 6′ is mounted) in closer distance to the centralportion of the tractor than to the first side area and the second sidearea.

The track device 8 has been brought into engagement with the ground 10,and accordingly a pressure is exerted against the ground 10 by the trackdevice 8. The track device 8 comprises two parallel hydraulic cylinders32 that have been extended in order to bring the track device 8 intoengagement with the ground 10.

FIG. 7 a) illustrates a schematic side view of a track device 8 of avehicle according to the invention in a “normal operation modeconfiguration”. The track device 8 comprises a track device member 22 (abelt) arranged along the periphery of a plurality of wheels. The forwarddirection Y is indicated by an arrow Y. The track device 8 comprises afirst segment having a first length L₁ and a second segment with asecond length L₂. A force F is applied in order to press the trackdevice 8 towards the ground.

In FIG. 7 b), it is shown that the track device 8 can be brought intoanother operation mode configuration by changing the configuration ofthe track device member 22 (the belt). The track device 8 is broughtinto a configuration in which the front portion of the track device 8having the length L₁ is angled relative to the (remaining) rear portionof the track device 8 having the length L₂.

This may be done when driving on soft ground (e.g. mud) in order toprevent the track device from getting under ground level. Thecircumference of the track device member 22 is kept constant since thedistance between the wheels indicated is kept constant (L₁ and L₂respectively).

FIG. 7 c) illustrates the track device 8 in a slightly otherconfiguration. This configuration may be an advantage when a vehicle isdriving in a very soft area (e.g. in mud).

The vehicle on which the track device 8 is mounted may comprise anysuitable means for changing the configuration of the track device 8. Themeans may be hydraulic drive means or electric drive means by way ofexample. The front portion of the track device 8 having the length L₁ isangled more relative to the (remaining) rear portion of the track device8 having the length L₂ than in FIG. 7 b).

FIG. 7 d) illustrates a schematic top view of a track device 8 of avehicle according to the invention. It can be seen that the track device8 can be displaced along the axis X extending perpendicular to thedirection of travel Y. The track device 8 may be displaced into a firstposition A or into a second position B as indicated with dotted lines.

Hereby, the track device 8 can be displaced in order to fit the specificdistances between rows of cultivated plant (e.g. berry trees, beets,potatoes, wheat, oats, or corn and other grain crops).

The vehicle according to the invention may comprise means for visuallydetecting the distance between rows of cultivated plant. The vehicle mayfurther comprise means for displacing the track device 8 in order to fitthe detected distance between the rows.

Any suitable means may be applied to displace the track device 8 andhereby change the configuration of the track device 8. The means may behydraulic drive means or electric drive means by way of example.

FIG. 8 illustrates a diagram of a proportional, integral and derivative(PID) control 80 comprising two hydraulic cylinders 62, each providedwith a piston 64 configured to press the track device according to theinvention towards the ground.

The PID control 80 comprises two pressure compensators 66 in fluidcommunication with the hydraulic cylinders 62. The pressure compensators66 may be filled with air, nitrogen or helium. The pressure compensators66 are in fluid communication with the track device of the invention andthe pressure compensators 66 are configured to reduce peak forces causedby the track device when driving over bumps and holes.

The connection points 72, 94 are configured to be connected to thehydraulic system of a vehicle (e.g. a tractor). In order to activate thetrack device according to the invention, hydraulic oil is pumped throughthe connection point 72, and the connection point 94 is opened (e.g. bymeans of a valve) in order to allow hydraulic oil to flow into ahydraulic tank (return line). A first coupling 74 is indicated next tothe connection point 72, while a second connection point 90 is indicatednext to the connection point 92.

By adjusting the variable set point 68 at the control box 70, one canopen the control valve 76 in order to send oil to the high pressure sideof the cylinders 62. This will force the track device to be movedtowards the ground until the oil pressure measured by the pressuretransmitter 86 equals the set point 68. A dead band of approximately 10bar may be accepted to avoid constant operation of the control valve 76.The control box 70 sends electrical control signals 94 (indicated by adotted line) to the control valve 76 and to the constant pressure valve78.

An adjustable constant pressure valve 78 will drain oil from thecylinders 62 if the set point 68 pressure is lower than the pressuremeasured by the pressure transmitter 86. Further, the control valve 76will add additional oil if the set point pressure 68 is larger than thepressure measured by the pressure transmitter 86. A manometer 82 isinstalled in order to provide visual inspection of the pressure withinthe system.

The pressure compensators 66 have accumulator-capacity to absorb shockscause by the track device when being in contact with bumps and holes.

In order to lower the track device, oil is alternated on the hydraulicconnection point 72, 92. A pilot-operated non-return-valve 92 ensuresthat oil is drained from the pressure side of the cylinders 62 bypassingthe control valve 76.

The system comprises a safety valve 88 and a non-return valve 84arranged next to the constant pressure valve 78

FIG. 9 a) illustrates a side view of a tractor trailer 2 according tothe invention. The tractor trailer 2 comprises a track device 8 that hasbeen brought into engagement with the ground 10. The vehicle 2 isprovided with a control box 106 adapted to activate activation means(e.g. a hydraulic cylinder or an electric actuator) in order to changethe vertical position of the track device 8 and/or the pressure withwhich the track device 8 engages the ground 10.

The vehicle 2 comprises a tyre pressure sensor 110 provided at the wheel6 and a velocity sensor 108 attached to the wheel 6. The tyre pressuresensor 110 and the velocity sensor 108 are configured to wirelesslycommunicate with the control box 106. It can be seen that the tyrepressure sensor 110 and the velocity sensor 108 send wireless signals112 to the control box 106.

Accordingly, the tyre pressure sensor 110 and the velocity sensor 108can detect pressure and velocity data and send????? the data to thecontrol box 106. The control box 106 can determine if the pressure withwhich the track device 8 engages the ground 10 should be unchanged orchanged (increased or decreased). By way of example, the control box 106may be configured to receive information about the speed of the vehicleand at the same time receive information from the velocity sensor 108.If the control box 106 detects that the speed of the vehicle exceeds thespeed of the wheel 6, it can be concluded that the road grip is poor.Accordingly, the control box 106 can control the actuator (e.g. ahydraulic cylinder) connected to the track device 8 to reduce thepressure with which the track device 8 engages the ground 10.

Hereby, the normal force acting between the wheel 8 and the ground 10will be increased, and the friction force will consequently beincreased. Accordingly, a sufficient road grip for driving the vehicle 2can be achieved.

FIG. 9 b) illustrates a side view of a tractor trailer 2 according tothe invention. The tractor trailer 2 comprises a track device 8 that hasbeen brought out of engagement with the ground 10.

FIG. 9 c) illustrates a perspective back view of the tractor trailer 2shown in FIG. 9 a). The tractor trailer 2 comprises a track device 8having two parallel hydraulic actuators 32 that have been extended inorder to bring the track device 8 into engagement with the ground 10.

FIG. 9 d) illustrates a perspective back view of the tractor trailer 2shown in FIG. 9 b). The tractor trailer 2 comprises a track device 8having two parallel hydraulic actuators 32 that are not fully extended.

FIG. 10 a) illustrates a track device 8 according to the inventionmounted on a first rotation device 100 according to the invention. Belowthe first rotation device 100, a Cartesian coordinate system with threeaxes X, Y, Z is shown. The axis Y indicates the direction of travel, theaxis X is the lateral direction, while the axis Z indicates the verticaldirection.

The first rotation device 100 comprises a base member 104 rotatablymounted to a shaft member 96 extending along the horizontal axis Y. Thetrack device 8 comprises two hydraulic actuators 32 extending betweenthe track member 22 and the base member 104 of the rotation device 100.

During normal operation, the hydraulic actuators 32 extend vertically.If required, the track member 22 and thus the hydraulic actuators 32 canbe rotated about the direction of travel Y. Hereby, an angulardisplacement of the hydraulic actuators 32 will occur. In FIG. 10 a),two angular displacements are indicated (with dotted lines). The angulardisplacements correspond to the indicated angle α.

This rotation will cause the track device 8 to be angled (θ) relative tohorizontal. Rotation of the rotation device 100 may be accomplished bymeans of any suitable hydraulic or electrical means. The control of therotation device 100 may be carried out by means of one or more detectedparameters e.g. measurements provided by means of sensors.

FIG. 10 b) illustrates a track device 8 according to the inventionmounted on a second rotation device 102 according to the invention. ACartesian coordinate system with three axes X, Y, Z is illustrated belowthe second rotation device 102. Like in FIG. 10 a), the axis Y indicatesthe direction of travel, the axis X is the lateral direction, while theaxis Z indicates the vertical direction.

The second rotation device 102 comprises an attachment member 50rotatably mounted to a shaft member 98 extending along the vertical axisZ. The track device 8 comprises two hydraulic actuators 32 extendingbetween the track member 22 and the attachment member 50.

During normal operation, the suspension members 20 extend along thedirection of travel Y. If required, the track member 22 and thus thehydraulic actuators 32 can be rotated about the direction of travel Y.Hereby, an angular displacement of the suspension members 20 will takeplace. In FIG. 10 b), two angular displacements are indicated withdotted lines. The angular displacements are indicated with an angle 3.This rotation will make it easier to turn the vehicle on which the trackdevice 8 is mounted.

It may be an advantage to apply a hydraulic or electrical actuator tomove (rotate) the rotation device 102.

FIG. 10 c) illustrates a tractor trailer 2 according to the inventionseen from the rear end. The tractor trailer 2 is provided with a firstwheel 6 and a second wheel 6′ and a track device 8 according to theinvention arranged in the centre area between the wheels 6, 6′.

A Cartesian coordinate system with three axes X, Y, Z is illustratedbelow the tractor trailer 2. Like in FIG. 10 a) and in FIG. 10 b), theaxis Y indicates the direction of travel, the axis X is the lateraldirection, while the axis Z indicates the vertical direction.

FIG. 11 A) illustrates a schematic side view of a portion of a vehicle 2according to an embodiment of the invention. The vehicle 2 comprises atrack device 8 arranged below the rotating shaft connecting the firstwheel 6 and the second wheel 6′ of the vehicle. The track device 8 isarranged to support the portion of the shaft that extends between thefirst wheel 6 and the second wheel 6′ of the vehicle 2. Accordingly, thetrack device 8 can relieve the pressure with which the wheel 6, 6′engage the ground 10.

FIG. 11 b) illustrates a schematic side view of the vehicle 2 shown inFIG. 11 a) in a configuration in which the track device 8 does notengage the ground 10.

FIG. 11 c) illustrates a schematic view of a track device 8 attached toa shaft 52 extending between a first wheel 6 and a second wheel 6′ bymeans of a first attachment member 114 and a second attachment member114′ connected to the track device 8 by means of a first connectionmember 116 and a second connection member 116′. The connection members116, 116′ may be a telescopic mechanical actuator, such as a hydrauliccylinder.

LIST OF REFERENCE NUMERALS

-   -   2 Vehicle (e.g. tractor trailer)    -   4 Motorised vehicle    -   6, 6′ Wheel    -   8 Track device    -   10 Ground    -   12 Frame member    -   14 Support member    -   16 Tipping member (telescopic arm)    -   18 Box member    -   20 Suspension member    -   22 Track member    -   24 Rear wheel    -   26 Front wheel    -   28 Top support wheel    -   30 Bottom support wheel    -   32 Actuator    -   34 Connection member    -   34′, 34″ Connection element    -   36 Base member    -   38 Second end portion    -   40 First end portion    -   42, 44 Joint    -   46, 48 Track device member    -   50 Attachment member    -   52 Shaft member    -   54 End portion    -   56 Central portion    -   58, 58′ Side area    -   60 Centre area    -   62 Hydraulic cylinder    -   64 Piston    -   66 Pressure compensator    -   68 Set point    -   70 Control box    -   72 Hydraulic connection point    -   74 Hydraulic coupling    -   76 Control valve    -   78 Constant pressure valve    -   80 Proportional, integral and derivative control    -   82 Manometer    -   84 Non-return valve    -   86 Pressure transmitter    -   88 Safety valve    -   90 Hydraulic coupling    -   92 Hydraulic connection point    -   94 Electrical control signal    -   96, 98 Shaft member    -   100, 102 Rotation device    -   104 Base member    -   106 Control box    -   108 Sensor    -   110 Sensor    -   112 Signal    -   114, 114′ Attachment member    -   116, 116′ Connection member    -   α, β Angular displacement    -   θ Angle    -   P, P₁, P₂, P₃ Pressure    -   F, F₁, F₂, F₃, F₄ Force    -   X, Y, Z Direction    -   A, B Position    -   F, F₁, F₂, F₃ Force    -   L₁, L₂ Length

1. A vehicle comprising at least a first wheel mounted in a first sidearea of the vehicle and a second wheel mounted in a second side area ofthe vehicle, which vehicle comprises a track device configured to bebrought into engagement with the ground, wherein the vehicle comprises acontrol member configured to adjust a pressure with which the trackdevice engages the ground, wherein the pressure is determined on thebasis of measurements performed by one or more detection membersconfigured to detect one or more variable parameters of the vehicle. 2.The vehicle of claim 1, wherein the one or more variable parameters ofthe vehicle are one or more of the following: a) slippage and/or roadgrip of one or more of the wheels; b) he axle load and/or the load ofthe vehicle or of a container of the vehicle; c) tyre pressure of one ormore of the wheels; d) measured motor power and/or the velocity of thevehicle; e) visual detection of the content in a container; f) pressurein a structure; g) distance from a predefined position to an object. 3.The vehicle of claim 1, wherein the vehicle comprises a control memberconfigured to adjust the pressure with which the track device engagesthe ground on the basis of geographical data measured by a sensor memberof the vehicle or received by the vehicle.
 4. The vehicle of claim 1,wherein the vehicle comprises means for bringing the track device into aconfiguration in which the track device is not in engagement with theground.
 5. The vehicle of claim 1, wherein the track device is motorizedfor driving the track device.
 6. The vehicle of claim 1, wherein thetrack device is detachably mounted to the vehicle.
 7. The vehicle ofclaim 1, wherein the track device is displaceable along an axisextending perpendicular to the direction of travel.
 8. The vehicle ofclaim 1, wherein the track device is movably, e.g. slidably, arranged atthe vehicle in such a manner that the track device may be rearranged. 9.The vehicle of claim 1, wherein the vehicle comprises means for ensuringthat the track device engages the ground with a predefined pressuredefined on the basis of measurements made by the vehicle.
 10. Thevehicle of claim 1, wherein the track device is arranged below a shaftconnecting the first wheel and the second wheel of the vehicle.
 11. Thevehicle of claim 10, wherein the track device is arranged to support aportion of the shaft that extends between the first wheel and the secondwheel of the vehicle.
 12. A method for controlling a tracked and wheeledvehicle comprising a track device configured to be brought intoengagement with the ground, which vehicle comprises a control memberconfigured to adjust a pressure with which the track device engages theground, wherein the method comprises the steps of: detecting one or morevariable parameters measured by one or more detection members; adjustingthe pressure with which the track device engages the ground on the basisof the detected parameter(s) or external information received by thevehicle.
 13. The method of claim 12, wherein the one or more variableparameters measured by one or more detection members are one or more ofthe following: a) slippage and/or road grip of one or more of thewheels; b) axle load and/or the load of the vehicle or of a container ofthe vehicle; c) tyre pressure of one or more of the wheels; d) measuredmotor power and/or the velocity of the vehicle; e) visual detection ofthe content in a container; f) pressure in a structure; g) distance froma predefined position to an object.
 14. The method of claim 12, whereinthe method comprises the step of adjusting the pressure with which thetrack device engages the ground on the basis of geographical datameasured by a sensor member of the vehicle or received by the vehicle.15. The method of claim 14, wherein the geographical data comprisesinformation about the soil type of the ground at the area below and/oraround the vehicle.